Provide a cpu setting to override default host setting #592
Description
It seems that sometimes the -cpu host option configures a CPU that cannot be used to create a VM. See for example rancher-sandbox/rancher-desktop#1291 (comment).
Changing to e.g. -cpu Haswell could fix the issue, but right now the only mechanism we have to change the setting is via the clumsy $QEMU_SYSTEM_X86_64 environment variable, that is really only meant for debugging.
I propose adding a cpu field to lima.yaml that defaults to host, but allows the user to switch to a different CPU.